Effect of 60Co- Irradiation on Tissue Structure and Cellular Morphological Structure of Panax notoginseng Leaves

The seeds of Panax notoginseng were irradiated with 0, 10,20, and 40 Gy 60Co- irradiation, respectively. The effects of 60Co- irradiation on tissue structure and cellular morphological structure of P. notoginseng leaves were observed and studied by transmission electron microscope (TEM), which provided a theoretical reference for P. notoginseg irradition breeding.The results of the electron microscope observation showed that there were varying degrees of impact and damage on the tissue structure and cellular morphological structure of P. notoginseng leaves by 60Co- irradiation and different structural changes were not synchronious. Compared with 0 Gy irradiation treatment,when the irradiation dose was 10 Gy, palisade tissue cells became two layers and cells arranged loosely;cell shapes distorted, the number of mitochondria increased slightly, nucleus and cell walls were damaged and cells appeared plasmolysis phenomenon. When the irradiation dose was 20 Gy,the irregular degree of spongy tissue cell shapes increased, cells arranged more loosely. The degree of damage of chloroplast,mitochondrion, nucleus and cell wall in cells was bigger and the plasmolysis became more serious. When the irradiation dose was 40 Gy, spongy tissue and palisade tissue were most affected, cell arrangement was extremely loose and the hierarchy was not clear. The amount of chloroplasts and mitochondria decreased significantly, the plasmolysis was most serious and the normal growth and development of P. notoginseng leaves was blocked. It might be concluded that the effect on the tissue structure and the damage degree of cellular morphological structure of P. notoginseng leaves tended to increase with increasing irradiation dose.The spongy tissue had better tolerance to 60Co- irradiation than palisade tissue, followed by chloroplasts and mitochondrial, and the proper radiation could increase the number of mitochondria;the nucleus was more sensitive to radiation.The above conclusions could provide theoretical basis for P.notoginseng breeding of different purposes and provide theoretical reference for choosing the most appropriate dose of irradiation mutation breeding.